@tris two things: I already said in my follow up post that if someone wants to build their own clients on top of XMPP and prefers MLS over OMEMO, the XMPP community is very open to that. A protocol is much more than just the encryption. They would still benefit from all the other things XMPP has solved.
A lot of what's in that blog post is ill-informed and bordering on disinformation and fear mongering.